Question 1098659: let n be the largest integer less than 10000 that leaves remainder 1 when divided 2,3,4,5,6,7 and 8.the sum of the digits of n is
Answer by Edwin McCravy(20060) (Show Source):
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Any integer which is 1 more than a multiple of all those
will leave remainder 1 when divided by any of those. Any
integer which is a multiple of all those is a multiple of
their least common multiple.
2,3,4,5,6,7,8 = 2,3,2x2,5,2x3,7,2x2x2
So the LCM must have 3 factors of 2, 1 factor of 3, 1 factor
of 5, and 1 factor of 7. So the LCM = 2x2x2x3x5x7 = 840, so
any number of the form 840k+1 will leave remainder 1 when
divided by 2,3,4,5,6,7 or 8.
We want the largest such integer less than 10000
840k+1 < 10000
840k < 9999
k < 9999/840
k < 11.90357143...
So the largest integer k can be is 11
840k+1 = 840(11)+1 = 9241 = n
The sum of the digits of n is 9+2+4+1 = 16
Edwin
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